1. Design Review: RoboSiM Robotic Surveillance in Motion
Bryan McDonnel
Michael Mize
Ryan Taylor
Miles Whittaker

2. Outline Project overview Project-specific success criteria
Block diagram
Component selection rationale
Packaging design
Schematic and theory of operation
PCB layout
Software design/development status
Project completion timeline
Questions / discussion

3. RoboSiM Overview Robotic surveillance vehicle Navigate to a target
Avoid obstacles
Survey target location by recording audio

4. Project Specific Success Criteria
Demonstrate an ability to:
Display the current status of the robot on an external display.
Read from and write to a portable media device.
Make navigational decisions based on sensor, GPS, and digital compass data.
Control the robot using steering and motor drive.
Capture and encode audio.

5. Block Diagram

6. Component Selection Microcontroller: PIC24H Audio encoding
G.711 needs 1 MIPS
Capable of 40 MIPS
Free libraries from Microchip
Numerous peripherals
2 SPIs, 2 I2Cs, 2 UARTs
Robust IDE
MPLAB and development board

7. Component Selection GPS Module: Skytraq VENUS Accurate
< 2.5m CEP
Configurable update rate
Up to 10 Hz
Form factor
Breakout board
SMA connector

8. Component Selection Sensors: Ultrasonic Range Multiple interface types
6” – 254” with 1” resolution: (Vcc/256)/in
Wide beam for general obstacle detection
Multiple interface types
Digital serial
Analog voltage
PWM

9. Packaging Design RP5 Chassis Motors Forward-mounted microphone
Tank treads
Small
Motors
6” per second nominal
Forward-mounted microphone
Forward and side-mounted ultrasonic sensors

10. Packaging Design
Top View

11. Packaging Design

12. Theory of Operation Obtain data from SD card and note current location
Validate SD card coordinates and initialize systems
Start motors and travel to destination while continuously sampling sensors
Navigate around objects using compass and sensors
At destination, sample microphone using ADC
Return to starting location

13. Theory of Operation/Schematics
Five Key Functional Blocks
Object Detection
Navigation
Motor Control & Power
Audio Capture
Display and Storage

14. Block Diagram

15. Microcontroller

16. Microcontroller
Reset
PICKIT-2

17. Microcontroller
Audio

18. Power - Battery Regulators designed to accept 8 – 11 V input
8.4V NiMH AA rechargeable battery pack used as input
2200 mAh
Buck regulators used to produce 7.2V and 3.3V output
Motors draw 2.45 A each at stall

19. Power

20. Motor Control

21. Navigation Digital compass and GPS used
GPS runs at 10 Hz, Digital compass at 20 Hz
Dead reckoning between GPS samples
GPS sends NMEA* string over UART that will be parsed to determine current location
Algorithm described in software narrative
*National Marine Electronics Association 0183 Standard

22. Object Detection Three ultrasonic sensors attached to chassis
Front-, left-, and right-facing
Sensors run in continuous scan mode at 20 Hz
Distance to object corresponds to 6.45 mV / in [(Vcc/512)/in]
Sensors sampled by ADC using 12-bit resolution

23. Audio

24. PCB Layout: Overview
Low-Power
High-Power

25. PCB Layout: Power Supply
3.3V Supply
7.2V Supply

26. PCB Layout: Power Supply
High Current
(up to 5.1A)
75mil traces

27. PCB Layout: Power Supply
Routed to shorten
current loops
(both regulators) 2 4 5 1 3

28. PCB Layout: Power Supply
Routed to shorten
current loops
(both regulators) 4 5 1 2 3

29. PCB Layout: Power Supply
Additional
caps
Redundant caps
to prevent brownout
during motor load
changes

30. PCB Layout: Motor Control
H-Bridge Controllers

31. PCB Layout: Motor Control
H-Bridge Controllers
High Current
(up to 5.1A)
75mil traces

32. PCB Layout: Motor Control
Data
Data & Power
Traces Separated
Power

33. PCB Layout: Motor Control
Planned Thermal
Relief Plane

34. PCB Layout: Microcontroller
PIC24H Microcontroller

35. PCB Layout: Microcontroller
four decoupling caps
placed close to pins

36. PCB Layout: Microcontroller
Two caps under board
to better utilize space

37. PCB Layout: Microcontroller
Unconnected pins
configured as outputs
and left floating

38. PCB Layout: Peripherals
Analog
Digital
SD Card & LCD Headers
Mic & Audio Amplifier
Ultrasonic Sensor
Inputs
GPS, Digital Compass,
& PICKIT Headers
Reset Circuit

39. PCB Layout: Peripherals
Analog
Digital
Separation of
analog & digital
interfaces

40. PCB Layout: Peripherals
Analog
Digital
Analog and switching lines cross at
right angles
(2 cases)

41. PCB Layout: Peripherals
Analog
Digital
Peripherals connected through headers to preserve board area & minimize traces
(9 headers)

42. Software Design Navigation Haversine Formula Only need three points
Used to calculate great-circle distances
Only need three points
Robot position:
Target position:
North pole:

43. Software Design
r = Radius of Earth

44. Software Design

45. Completion Timeline Week Date Task Notes 9 12-Mar
Final Schematic/Layout 10
19-Mar
Software Development
Spring Break 11
26-Mar
PCB Assembly 12
2-Apr
PCB Assembly Complete
External Software Complete 13
9-Apr
Software Complete, Debug
Embedded Software Complete 14
16-Apr
Field Testing 15
23-Apr 16
30-Apr
Testing Complete, Demonstration

46. Questions?